/Engine/Source/Editor/UMGEditor/Public/WidgetBlueprintEditorUtils.h
static void SetTextureAsAssetThumbnail ( [UWidgetBlueprint](API\Editor\UMGEditor\UWidgetBlueprint) * WidgetBlueprint, [UTexture2D](API\Runtime\Engine\Engine\UTexture2D) * ThumbnailTexture )